Hi all
We're currently fighting with knowledge extraction about opening/closing
days for tourism facilities (hotels, restaurants, museums, campings ...).
Information can be found in terms of closing and/or opening days during
a period, such as :
"Widget Museum is open in 2008, from March 1st to October 31st, closed
on Sunday and Tuesday".
NLP can extract the following description (1)
:WidgetMuseum :openingPeriod _:p1
_:p1 :begins 2008-03-01
_:p1 :ends 2008-10-31
_:p1 :closingDay :Tuesday
_:p1 :closingDay :Sunday
In an open world, we have no way to know if this is a complete
description, and can't infer that Widget Museum is open on Monday.
The other way round, if the information is given in terms of opening days,
"Widget Museum is open in 2008, from March 1st to October 31st, on
Monday, Wednesday, Thursday, Friday and Saturday".
Which yields the description (2)
:WidgetMuseum :openingPeriod _:p2
_:p2 :begins 2008-03-01
_:p2 :ends 2008-10-31
_:p2 :openingDay :Monday
_:p2 :openingDay :Wednesday
_:p2 :openingDay :Thursday
_:p2 :openingDay :Friday
_:p2 :openingDay :Saturday
... we can't infer that Widget Museum is closed on Tuesday and Sunday.
IOW there is no way to identify logically _:p1 and _:p2 in an open world.
Supposing (1) is the standard target description required by the
ontology used in the system, I thought possible to write, in our closed
world, a SPARQL CONSTRUCT query which would yield (1) from (2).
But thinking twice, my hunch is now that it is impossible, because of
the implicit open world assumption made by SPARQL.
Has someone already dealt with such issues? Any pointer welcome.
Thanks for your help
Bernard
--
*Bernard Vatant
*Knowledge Engineering
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*Mondeca**
*3, citÃ Nollez 75018 Paris France
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